Impact resistant door skin, door including the same, and method of manufacturing an impact resistant door skin from a pre-formed door skin

ABSTRACT

An impact resistant door skin, a door including the same, and a method of manufacturing an impact resistant door skin from a pre-formed door skin are provided. The method includes the steps of providing at least one preformed door skin and applying adhesive to a rear side of the at least one preformed door skin. A fiberglass mesh mat is pressed onto the rear side of the at least one preformed door skin. Then, chopped glass fibers coated with adhesive are sprayed onto the rear side of the at least one preformed door skin using a chopper gun to form a layer of chopped glass fibers on the fiberglass mesh mat. The performed door skin may be a molded door skin having at least one recessed panel formed therein.

CROSS REFERENCE TO RELATED APPLICATION AND CLAIM TO PRIORITY

This application is based on provisional application Ser. No.61/035,780, filed Mar. 12, 2008, the disclosure of which is incorporatedherein by reference and to which priority is claimed under 35 U.S.C.§119(e).

FIELD OF THE INVENTION

The present invention relates to an impact resistant door skin, a doorincluding the same, and a method of manufacturing an impact resistantdoor skin from a pre-formed door skin.

BACKGROUND OF THE INVENTION

As known in the art, door facings also known as “door skins” may besecured to a support structure or frame to form a hollow core door. Suchfacings may be molded from a polymeric material, such as sheet moldingcompound (“SMC”). SMC may be molded to form a door facing including oneor more depressions or grooves, such as one or more square orrectangular depressions. These depressions may define the perimeter ofone or more simulated panels. Alternatively, the facings may be flush.

The door facings are secured to opposing sides of the frame, forminghollow spaces between the facings. A core component or material issometimes used to fill the hollow spaces. Conventional core materialsfor use in hollow core doors include corrugated cardboard, paper, foam,or fiberboard.

It is sometimes desirable to provide an exterior door that can withstandimpacts from flying debris, such as in a high velocity wind zones. Doorsare sometimes required to pass certain performance tests, such as thosedeveloped by the American Society of Testing Materials (ASTM) which testthe performance of doors exposed to the effects of windstorms and impacttesting. Doors may also be required to meet regional performance testswithin a particular state, such as Florida. The Florida Building Codesets out stringent requirements for building components so thatbuildings can withstand hurricanes and other severe weather conditions.Impact testing for wind-borne debris is performed on exterior doors andother building components. Sections 1625 and 1626 of the Code providethe specifications for the impact testing. For “large missile” impacttests, a 9 pound two-by-four is projected at the surface of the testspecimen at a speed of about 50 feet per second (34.1 miles per hour)using a compressed air cannon. The large missile test is used onbuilding components that will be located less than 30 feet above theground. In this test, each specimen receives two impacts, one in thecenter and one in a corner of the specimen. Once the large missiletesting is completed, a fatigue load testing is performed on thespecimen.

During the fatigue load testing, a cyclic large predetermined pressureload is applied to the test specimen to ensure that the specimen doesnot detach from its respective mounting. The pressure is applied by acompressed air supply blower during forward test loading periods andreverse test loading periods in which a pressure differential based on awind velocity of 75 miles per hour is formed across the entry door orbuilding component in a testing chamber. Permanent deformation and themaximum deflection are recorded for each specimen. An exterior door orother building component “passes” these tests if three specimens rejectthe two missile impacts without penetration and resist the cyclicpressure loading with no crack forming that is longer than 5 inches andwider than 1/16 of an inch.

The “small missile” impact test includes projecting 30 small steel ballsof about half a pound and 5/16 of an inch in diameter at the exteriorbuilding component at different locations at a speed of 130 feet persecond (88.6 miles per hour). The “small missile” impact test isperformed on building components that will be located more than 30 feetabove the ground. Once the small missile impact test is completed, thefatigue load testing is performed by applying the cyclic pressure todetermine whether the specimen will detach from its mountings. Permanentdeformation and the maximum deflection are recorded for each specimen.An exterior door or other building component “passes” these tests ifthree specimens reject the small missile impacts without penetration andresist the cyclic pressure loading with no crack forming that is longerthan 5 inches and wider than 1/16 of an inch.

Testing Application Standards (TAS) sections 201-94, 202-94, and 301-94provide the protocols for the large missile, small missile, and fatigueloading impact tests.

Various attempts have been made to provide a hollow core door that canwithstand impact testing. One design provides a hollow core door havinga mat disposed within the door cavity and between the opposing doorfacings. A cementitious material is poured around the mat. Such doorsare relatively expensive and difficult to assemble. In addition, theyare relatively heavy, and therefore difficult to store, transport andinstall. Other designs provide for metal door facings. Such doors arealso relatively expensive. In addition, they are often less desirable toconsumers because they lack aesthetic detail, and may rust and dent.

Conventional impact resistant doors are typically made impact resistantduring the manufacturing processes used to fabricate the door skinsthemselves. Thus, these doors are manufactured specifically to be impactresistant and are then placed on the market. However, consumers havelittle choice in the variety of doors that can be made high impactresistant. That is, consumers typically have a limited number of optionsfor selecting from among styles and sizes of hollow core doors that aremade impact resistant.

Additionally, the manufacture of impact resistant hollow core doorstypically requires a substantial amount of equipment and capital, thusmaking impact resistant doors relatively expensive to manufacture.

Therefore, there is a need for an impact resistant door that overcomessome or all of the above noted problems and disadvantages.

SUMMARY OF THE INVENTION

A method of manufacturing a high impact resistant door skin includes thesteps of providing at least one preformed door skin and applyingadhesive to a rear side of the at least one preformed door skin. Afiberglass mesh mat is pressed onto the rear side of the at least onepreformed door skin. Then, chopped glass fibers coated with adhesive aresprayed onto the rear side of the at least one preformed door skin usinga chopper gun to form a layer of chopped glass fibers on the fiberglassmesh mat. The preformed door skin may be a molded door skin having atleast one recessed panel formed therein. The fiberglass mesh mat may becontoured to the shape of the molded door skin.

A method of reinforcing a plurality of molded preformed door skins ofdifferent styles and sizes includes the steps of applying a firstadhesive layer to a rear side of each of the molded preformed doorskins. Then, a first continuous fiberglass reinforcement layer isapplied on the rear sides of each of the molded preformed door skins sothat the first adhesive adheres the first continuous fiber reinforcementlayers to the preformed door skins. Chopped fiberglass strands arecoated with a second adhesive, and a second non-continuous fiberreinforcement layer is formed on each of the first continuous fiberreinforcement layers by applying the chopped fiberglass strands thereto.

A high impact resistant door skin usable in a hollow core door includesa preformed door skin having at least one recessed panel formed therein.A fiberglass mesh mat is adhered to a rear side of the at least onepreformed door skin. The fiberglass mesh mat is contoured to the atleast one recessed panel. A layer of chopped glass fibers coated withadhesive is disposed on the fiberglass mesh mat.

An impact resistant door includes a peripheral frame; and first andsecond door skins secured to opposing sides of the frame. At least oneof the skins includes a rectangular sheet of molded hardened polymericmaterial having first and second opposing major surfaces, a fiberglassmesh mat adhered to a rear surface of the at least one skin so that thepolymeric material does not permeate the fiberglass mesh mat, and alayer of chopped glass fibers coated with adhesive disposed on thefiberglass mesh mat.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevatational view of an exemplary hollow core door;

FIG. 2 is a fragmentary cross-sectional view taken along line 2-2 ofFIG. 1;

FIG. 3 is a flowchart of a method of manufacturing an impact resistantdoor skin from a preformed door skin, such as the door skins shown inFIGS. 1 and 2, according to an embodiment of the present invention;

FIG. 4 is a fragmentary cross-sectional view of a molded impactresistant door skin according to another embodiment of the presentinvention;

FIG. 5 is fragmentary cross-sectional view of a molded door skin beingpositioned in a bag press assembly in accordance with the method shownin FIG. 3; and

FIG. 6 is a fragmentary cross-sectional view of a molded door skin beingsprayed with chopped glass fibers in accordance with the method shown inFIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the embodiments and methods ofthe invention as illustrated in the accompanying drawings, in which likereference characters designate like or corresponding parts throughoutthe drawings. It should be noted, however, that the invention in itsbroader aspects is not limited to the specific details, representativedevices and methods, and illustrative examples shown and described inthis section in connection with the preferred embodiments and methods.The invention according to its various aspects is particularly pointedout and distinctly claimed in the attached claims read in view of thisspecification, and appropriate equivalents.

As best shown in FIGS. 1 and 2, an exemplary hollow core door 1 includesmolded door skins 7 and 9. The door skins 7 include three-dimensionalrecessed panels 3 and raised panels 5 and may be manufactured from sheetmolding composition (SMC) or other suitable polymeric material. Doorskins 7 and 9 of door 1 are adhesively secured to door frame 15, such aswith polyvinyl acetate. Those skilled in the art will recognize thatframe 15 extends about the periphery of rectangular door skins 7 and 9and door 1, and typically includes two parallel wooden stiles extendingalong longitudinal edges of the door and two parallel wooden rails atthe bottom and top of the door. Skins 7 and 9 are spaced apart from oneanother by frame 15 to form hollow core area 11 which can be filled withfoam or the like. That is, the hollow core area 11 may be filled with anexpanded foam insulating material defining an insulating core of thedoor 1, or a foam insert may be separately manufactured and disposed inthe hollow core area 11 to provide sound and thermal insulation as wellas providing the door 1 with the proper weight. A plastic foam or apolyurethane foam is suitable for such doors. Alternatively, the hollowcore area 11 may be filled with synthetic or natural fibers. While themethods of the present invention are described below with reference tomolded door skins 7 and 9 having at least one recessed panel, it shouldbe understood that the method of reinforcing a preformed door skin canalso be used to reinforce flush door skins, which have no recessedpanels.

Prior to assembling the door 1, preformed molded door skins 7 and 9 maybe reinforced according to the methods and processes of the presentinvention. As best shown in FIG. 3, the door skins 7 and 9 can bereinforced have been molded or preformed at step S20. At step S22, aurethane adhesive is applied to the rear side of the preformed door skin7, 9. The urethane adhesive may be a one component moisture curedurethane adhesive applied to the rear side of the door skin 7, 9, suchas by an adhesive roller. At step S24, a fiberglass mesh 40, best shownin FIGS. 4, 5, and 6, is applied to the rear side of the door skin 7, 9.The fiberglass mesh 40 is a continuous fine meshed fiberglass mat. Instep S22, the adhesive can alternatively be applied to the fiberglassmesh 40 before it is positioned on the rear side of the preformed doorskin 7, 9. The fiberglass mesh 40 is then pressed against the rear sideof the door skin 7, 9 by a bag press assembly 32 at step S24, as bestshown in FIG. 5.

As shown in FIG. 5, a bag press assembly 32 includes a lower platen 34and an upper platen 36. The lower platen 34 is preferably heated. Theupper platen 36 includes a membrane 38 that is inflatable to conform tothe shape of the preformed door skin 7, 9. As the membrane 38 fills withair, it expands and assumes a shape complementary to that of the doorskin 7, 9, thereby also causing the fiberglass mesh 40 to conform to theshape of the door skin 7, 9. Accordingly, a fiberglass mesh 40 can beadhered to the door skin 7, 9 by inflating the membrane 38, pressing thedoor skin 7, 9, and curing the urethane adhesive.

Because of the bag press assembly 32, the fiberglass mesh 40 can becontoured to molded door skins of various shapes, sizes, and styles. Thefiberglass mesh 40 is sized to correspond to the preformed door skin 7,9. During the pressing step, the fiberglass mesh 40 is adhered to thesurface of the preformed door skin 7, 9 without affecting or changingthe structural integrity of the preformed door skin 7, 9 itself. Thus,the preformed door skin 7, 9 can be manufactured using conventionalmethods to provide specific structural, functional, and/or aestheticqualities to the preformed door skin 7, 9 that are maintained during thereinforcement of the door skin 7, 9. Also during the pressing step(S24), the adhesive may not be fully cured between the fiberglass mesh40 and the preformed door skin 7, 9. When the adhesive is moisture curedadhesive, the adhesive may continue to cure due to the moisture in theair, after the pressing step is completed.

In an exemplary embodiment of the present invention, the bag pressassembly 32 is heated to between 140-160 degrees Fahrenheit, pressurizedto between 10 and 14 bars, and applied to the mesh 40 for 1 to 5minutes. Alternatively, a catalyzed adhesive can be used in the pressingstep (S24) to adhere the fiberglass mesh 40 to the preformed door skin7, 9. In this case, the bag press assembly 30 can be applied to cure theadhesive at a temperature below 140 degrees Fahrenheit, for example, 120degrees Fahrenheit. Other adhesives may also be used in this step of theprocess.

In an alternative embodiment of the present invention, a press assembly(not shown) having platens specifically contoured to the preformed doorskin 7, 9 may be used instead of the bag press assembly 32 shown in FIG.5.

Referring to FIG. 3, once the fiberglass mesh 40 is contoured andadhered to the door skin 7, 9, a layer 42 of chopped glass fibers coatedwith urethane adhesive is applied to the exposed surface of the mesh 40to adhere to the door skin 7, 9. The layer 42 of chopped glass fibersmay be applied by a chopper gun 44, which sprays the chopped glassfibers directly onto the fiberglass mesh 40, as best shown in FIG. 6.The chopped glass fibers may be uniform length or variable length.

The urethane adhesive coated to the glass fibers is preferably anunreacted two component urethane system. The two component system reactswith moisture in the air and provides a hard layer that further improvesimpact resistance. For example, as best shown in FIG. 6, the chopper gun44 may be supplied with an unreacted urethane resin base and a catalystfor mixing to form the urethane based adhesive. The chopper gun 44 isalso supplied with glass fiber which is coated with the urethane basedadhesive. The coated glass fiber is then chopped by the chopper gun 44and sprayed by high pressure air onto the door skin 7, 9.

The two components of the urethane system may be commercially availableBASF Elastocoat S 55090R Resin as the unreacted urethane base andElastocoat S 55090T Isocyanate as the catalyst for the reaction. Theglass fiber may be commercially available PPG HYBON 6700 Glass strandapplied using a Gusmer H20/35 with Probler Spray gun.

Chopper guns typically deposit chopped glass fibers randomly to form achopped glass fiber mat held together by adhesive. Because theorientation of the reinforcing chopped glass fibers is random andnon-oriented, it is difficult to deposit these chopped glass fibers in auniform manner along a contoured or molded article, such as thepreformed door skin 7, 9. Thus, it is also difficult to form a choppedglass fiber mat with a uniform weight, distribution, and strength on thepreformed door skin 7, 9.

However, continuous fiberglass mesh mats are flexible and are easilyconformed to non-planar shapes and molds. Thus, by applying thefiberglass mesh 40 to the rear surface of the door skin 7, 9 prior toapplying the layer 42 of chopped glass fibers, the reinforcement layers40, 42 applied to the door skin 7, 9 can be contoured more precisely andefficiently to the shape of the molded preformed door skins 7, 9. Thefiberglass mesh 40 provides a base which rounds or smoothes out anysharp or dramatic contours or molding shapes so that the chopped glassfibers can be more easily uniformly deposited on the molded preformeddoor skin 7, 9. As a result, the reinforcement layers 40, 42, which eachadd a substantial degree of additional impact resistance to the doorskin 7, 9, can be stably secured and uniformly applied to the preformeddoor skin 7, 9 so that the weight distribution, the tensile strength,and impact resistance of the door skin 7, 9 are substantially uniformthroughout the door skin 7, 9.

In alternative embodiments, other types of adhesive can be used to coatthe chopped glass fibers. For example, a polyurea coating may be used tocoat the chopped glass fibers. It will be appreciated by one of ordinaryskill in the art that various types of coatings may be used for thechopped fibers.

As best shown in FIG. 4, a molded impact resistant door skin 46according to an embodiment of the present invention includes thepreformed door skin 7, 9, the layer 40 of fiberglass mesh disposed onthe rear side of the preformed door skin 7, 9, and the layer 42 ofchopped glass fibers disposed on the fiberglass mesh 40.

The degrees of impact resistance added by each of the continuous fiberwoven mesh layer 40 and the non-woven chopped glass layer 42 providesthe door skin 46 with the ability to withstand high impact winds,debris, etc. commonly associated with hurricanes, tornadoes, and othernatural disasters. A high impact resistant hollow core door according toan embodiment of the present invention may be similar to the hollow coredoor 1 shown in FIGS. 1 and 2, where the door skin 46 is used instead ofthe door skin 7, 9.

In order to manufacture the impact resistance door skin 46 and/or a doorincluding the door skin 46, an entire plant need not be dedicated tomanufacturing the door skins 46. Because the methods and processesdescribed above can be used with any type of preformed door skin, thesedoor skins can be made impact resistant after conventional polymericdoors skins have been manufactured. Thus, an end consumer or contractorcan special order any type of door skin to be made into a high impactresistant door skin according to the embodiments of the presentinvention. As a result, high impact resistant doors and door skins canbe made of any style and/or size of door skin efficiently, without ahigh degree of equipment changeover, with minimal capital, lowproduction costs, and without accumulating a large inventory of highimpact resistant hollow core doors.

The following exemplary embodiment of the invention illustrates one ofthe advantages of the present invention. A method of producing highimpact resistant doors includes receiving purchase orders for hollowcore doors selected by a customer. Some of the purchases orders areassociated with a high impact resistant specification selected by thecustomer. The methods and processes of FIGS. 3 to 6 can be applied todoor skins of the selected hollow core doors associated with the highimpact resistant specification to reinforce the door skins, after themanufacturing of the door skins is complete. These methods and processesmay be performed at the same manufacturing plant at which the door skinsare manufactured, or they may be performed at a separate manufacturingplant dedicated to reinforcing preformed door skins according to themethods and processes described above.

Alternatively, the high impact resistant specification may be appliedautomatically to hollow core doors that are to be shipped to a certaingeographical location(s) that is prone to high impact winds, hurricanes,tornadoes, etc. In this case, the manufactured door skins for hollowcore doors would be automatically reinforced.

The reinforcement of the door skins of the hollow core doors associatedwith the purchase orders may be selected/controlled as described aboveusing computer software for generating purchase orders.

It should be understood that although the embodiments of the inventionhave been described above with reference to making door skins highimpact resistant, the methods and processes of the present invention canalternatively be used to make other building components high impactresistant. For example, a fiberglass mesh can be applied to a contouredor molded building component using a press in a similar manner as setforth above. Then a chopper gun may be used to spray chopped glassfibers onto the fiberglass mesh so as to make the contoured buildingcomponent resistant to high impacts.

Although a few embodiments of the present invention have been shown anddescribed, it will be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe appended claims and their equivalents.

1. An impact resistant door, comprising: a peripheral frame; and firstand second door skins secured to opposing sides of said frame, at leastone of said skins comprising a pre-molded polymeric material comprisingfront and rear opposing major surfaces, a fiberglass woven mesh matadhered to the rear major surface of at least one skin, and a layer ofnon-woven and randomly oriented chopped glass fibers adhesively securedto said fiberglass woven mesh mat.
 2. The impact resistant door of claim1, wherein said woven mesh mat is secured to said rear major surfacewith a moisture curable adhesive.
 3. The impact resistant door of claim2, wherein said fibers are adhered to said woven mesh mat with a twocomponent urethane adhesive.
 4. The impact resistant door of claim 3,wherein said door skins are formed from said preformed polymericmaterial, said at least one skin having a panel molded therein.
 5. Theimpact resistant door of claim 4, wherein said woven mesh mat conformsto said rear major surface.
 6. The impact resistant door of claim 4,wherein said woven mesh mat is adhered to only one of said door skins.